The term ‘piezoelectricity’ is used to describe dielectric materials that produce electrical charges across their boundaries due to the application of a mechanical stress, which is called the direct piezoelectric effect [12]. The indirect (or converse) piezoelectric effect happens when the material is subjected to an electrical field which causes a mechanical strain of the material. In piezoelectric materials, the relationship between induced charges per unit area and the applied stress is linear and reversible. In inorganic piezoelectric crystalline materials, such as aluminum nitride (AlN) [13], this phenomenon happens due to the arrangement of ions in the crystal structure of the dielectric material.The internal polarization of the material changes linearly with the applied stress, causing an electrical field to develop across the material boundary. Such crystal structures are said to lack inversion symmetry [14]. For an AlN thin film, the piezoelectric coefficient is highly dependent on the crystal orientation of the film, which cannot be changed after deposition. Alternatively, in a ferroelectric material, such as lead zirconate titanate (PZT), the internal dipoles of the material can be reoriented by the application of an external electric field, leaving a remanent polarization at zero applied electric field [3]. This remanent polarization also changes with the applied stress and this is where piezoelectricity takes place. So every ferroelectric material is piezoelectric but not every piezoelectric material is ferroelectric.